There’s a lot of talk about entropy in brain activity as of late. Particularly in relation to how the psychedelic drugs alter brain activity. Once thought of as a solution or explanation for the effects of psychedelic drugs on the brain (Carhart-Harris et al. 2014), I’d argue that it has now run its’ course, coming under further scrutiny, at least by a few people (Haley Dourron I’m looking at you!), myself included. Especially since the discovery that coffee increases brain entropy too (Chang et al. 2018). The idea that entropy was an explanation for psychedelic effects was proposed and hyped by Karl Friston and Robin Carhart-Harris, more recently dubbed the anarchic brain hypothesis (Carhart-Harris & Friston 2019). This essay is not here to challenge the claim that psychedelics induce brain entropy but instead, that brain entropy is explanatory of the psychedelic state.
Let’s see what the entropic brain hypothesis states about entropy (Carhart-Harris et al. 2014):
At its core, the entropic brain hypothesis proposes that the quality of any conscious state depends on the system’s entropy measured via key parameters of brain function. Entropy is a powerful explanatory tool for cognitive neuroscience since it provides a quantitative index of a dynamic system’s randomness or disorder while simultaneously describing its informational character, i.e., our uncertainty about the system’s state if we were to sample it at any given time-point. When applied in the context of the brain, this allows us to make a translation between mechanistic and qualitative properties. Thus, according to this principle, increased subjective uncertainty or “puzzlement” accompanies states of increased system entropy.
I suspect that organized brain activity or low entropy represents learned, reflexive, and habituated activity. This kind of activity is efficient. It is essentially the point of learning. When we try to solve new mental problems, we must try different solutions until something works. This means we do more things to solve a problem than we do to engage in a learned reaction script that responds to already-solved problems. Solving problems allows us to reduce the noise of possible reactions we could have in response to a problem. The solution(s) that we rest on after a problem is considered by us to be solved, should be a single or very few possible solutions. This means we can identify the problem in the future and quickly form a decision or response to solve that problem efficiently, rather than ruminating on possible ways to solve it. Entropy may simply represent the chaotic process of brain activity that is activated when trying to form new solutions to perceived problems.
Why might caffeine increase brain entropy? What does this suggest?
Caffeine is known to produce motivating and anxiogenic effects (at least in rats; are there no human studies on caffeine and motivation??) (Sheppard et al. 2012; Rogers et al. 2010). Consider what this means. Motivation is the desire we have to solve perceived problems. When we are unmotivated, it means that we do not perceive the problems around us to be significant enough to address, although there are many factors to this and it isn’t that simple. For the purpose of this article, we will focus on the factor of perceiving things to be problems. A dirty room may seem “okay” enough for us in the unmotivated state. Then we drink some coffee and suddenly we find ourselves motivated to address problems. Coffee may make smaller problems appear as more time-worthy or more motivating. At the extreme end, we may find ourselves frozen with anxiety as small problems have become major ones, distressing us to the point that motivation is not a solution anymore as we are crippled by the overwhelming bother of the problems around us.
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The increase in entropy observed from caffeine use may be a sign that we are now motivated to think about many things that we normally found too un-arousing and unmotivating. The motivation may cause us to engage in problem-solving, which I would expect to be more complex and chaotic than scripted, reflexive, or automatic responses. More activity must be tried before it is determined which activity is suitable and which should be avoided.
In contrast to what one might intuit, ADHD has been linked to decreased entropy, which correlated with severity of symptoms (Sukunbi et al. 2013). This would fit with the motivation concept being proposed here since ADHD is often thought to involve poor motivation and hypo-arousal (Mayer, Wyckoff, & Strehl 2016). Hypo-arousal may lead the ADHD individual to not dwell so much on solving problems. Stimulants like coffee (but not necessarily coffee itself) are also used to treat ADHD. Keep in mind, it isn’t clear whether common ADHD drugs increase entropy. Another thing: a review has suggested that ADHD may not be related to hypo-arousal of the autonomic nervous system specifically (Bellato et al. 2020). Though they do mention that medication may have confounded the measurement of ANS arousal because they have been found to arouse the ANS.
One of the newer ideas proposed by Robin Carhart-Harris is one that I am much more fond of. He proposes that under the influence of psychedelics we find ourselves having “relaxed beliefs”. In essence, he posits that our thinking is more loose or freed from the confines of it’s normal inflexible thinking patterns. This is the REBUS model for psychedelic effects (Carhart-Harris & Friston 2019). While I still have some skepticism of the ideas proposed in this model, it fits much more with my own hypothesis on the matters. I suspect that psychedelics may interrupt reflexive reactions we formed through learning. This could explain why these drugs seem to attenuate addiction and trauma, both of which are arguably strong forms of reward and stress (or punishment) learning. It is as if we become so compelled to follow reaction scripts that we are unable to escape them. This may not be different from REBUS, but I still don’t fully understand the extent of Robin’s beliefs on this topic.
By disrupting reflexive reaction scripts, we may find ourselves pressured into a state of existence that can no longer run on auto-pilot. This sends us straight into what many call “the present moment” (as if anything else even exists). Every experience is ripe with unsolved problems after the ingestion of the drug. It is as if we blocked our solutions, forcing us to constantly look at our present experience as if it were novel and unsolved. That very feeling that things are “novel” may simply be that we are processing more of the incoming stimuli in order to find solutions. Once we form solutions we may turn down our awareness to the “present moment” because a lot of stimuli is deemed to be irrelevant to one’s goals. The goals have refined reaction scripts that turn behavior into something like automatic reflexes, which are much faster and more useful than trying to figure out all the little details of the experience.
This may be why people find new ways to look at life under the influence of psychedelic drugs. It is as if the old way of looking at life was inhibited and the person has no other choice but to confront a new way of seeing. Whatever reality is seen during these experiences likely still conforms to the person’s knowledge base and cultural information. What we know as semantic information may still apply during these experiences. The ways in which we assess or form conclusions about the semantic knowledge that we have may change though. The therapeutic effects may even rely on effects like these. People may normally resist confronting their issues due to cognitive dissonance, but under the influence of the psychedelic drug, the script that was formed in response to that cognitive dissonance may vanish and leave the person with a new awareness of the situation and the choices they have to respond to the situation. Essentially one may realize that our reflexes are poisoning us in many cases.
Things we should test for entropy:
- Novel experiences.
- All stimulants (maybe brain entropy is measuring arousal).
- Unmedicated ADHD patients.
- Trying to solve puzzles (perhaps it would need to be specific types of puzzles).
- Maybe sleep?
. . .
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Bellato, A., Arora, I., Hollis, C., & Groom, M. J. (2020). Is autonomic nervous system function atypical in attention deficit hyperactivity disorder (ADHD)? A systematic review of the evidence. Neuroscience & Biobehavioral Reviews, 108, 182-206.
Carhart-Harris, R. L., Leech, R., Hellyer, P. J., Shanahan, M., Feilding, A., Tagliazucchi, E., … & Nutt, D. (2014). The entropic brain: a theory of conscious states informed by neuroimaging research with psychedelic drugs. Frontiers in human neuroscience, 8, 20.
Carhart-Harris, R. L., & Friston, K. J. (2019). REBUS and the anarchic brain: toward a unified model of the brain action of psychedelics. Pharmacological reviews, 71(3), 316-344.
Chang, D., Song, D., Zhang, J., Shang, Y., Ge, Q., & Wang, Z. (2018). Caffeine caused a widespread increase of resting brain entropy. Scientific reports, 8(1), 1-7.
Mayer, K., Wyckoff, S. N., & Strehl, U. (2016). Underarousal in adult ADHD: how are peripheral and cortical arousal related?. Clinical EEG and neuroscience, 47(3), 171-179.
Rogers, P. J., Hohoff, C., Heatherley, S. V., Mullings, E. L., Maxfield, P. J., Evershed, R. P., … & Nutt, D. J. (2010). Association of the anxiogenic and alerting effects of caffeine with ADORA2A and ADORA1 polymorphisms and habitual level of caffeine consumption. Neuropsychopharmacology, 35(9), 1973-1983.
Sheppard, A. B., Gross, S. C., Pavelka, S. A., Hall, M. J., & Palmatier, M. I. (2012). Caffeine increases the motivation to obtain non-drug reinforcers in rats. Drug and alcohol dependence, 124(3), 216-222.
Sokunbi, M. O., Fung, W., Sawlani, V., Choppin, S., Linden, D. E., & Thome, J. (2013). Resting state fMRI entropy probes complexity of brain activity in adults with ADHD. Psychiatry Research: Neuroimaging, 214(3), 341-348.